New iterative decoding of variable length codes with turbo-codes

A new joint source-channel (JSC) turbo-decoding scheme, with three soft-in/soft-out (SISO) modules, is presented for variable length coded sources protected by a turbo-code. This new scheme offers the advantage to combine the powerfulness of the used turbo-code with the robustness of the reversible variable length codes (VLC), and moreover with a decoding complexity close (or less) to the one of the turbo-code alone. The performance due to the turbo-code alone leads to an increased freedom in the VLC design depending on the application -, and suggests to revisit the VLC distance criteria investigated in R. Bauer and J. Hagenauer (March 2001). The decoding algorithm for this three SISO modules scheme is briefly presented in the framework of the Bayesian networks. Compared with previous JSC turbo-decoders and with a classical turbo-code, simulation results show the relevance and the superior performance of the proposed scheme.